蓝藻Anabaena 7120的吸氢及其和固氮活力的关系

分子氢通过氢酶活动支持蓝藻固氮。氢酶活性高低变化规律与蓝藻固氮活性大小在趋势上是一致的。氢对固氮产生的效用与蓝藻本身所处的内外界生理条件也有一定的联系。但是,正如前文曾经指出过的,蓝藻的吸氢特性和包括固氮在内的其它生理生化功能的关系,都还没有得到完全的阐明。本文以具有不同固氮活力的蓝藻Ana-     

湖泊蓝藻水华发生机理研究进展

蓝藻水华是富营养化湖泊常见的生态灾害,通过产生毒素、死亡分解时使水体缺氧和破坏正常的食物网威胁到饮用水安全、公众健康和景观,会造成严重的经济损失和社会问题,揭示其发生机理是进行防治的基础。综述了蓝藻水华发生机理的主要假说和证据,主要分为环境因子(营养盐、氮磷比、温度、微量元素、浮游动物牧食、水文和气象条件等)和生理生态特性(伪空泡、胶质鞘、CO2浓缩机制、适应低光强、贮藏营养物质、防晒、产毒素和固氮等)两个方面;评述了主要新理论,展望了今后的研究。到目前为止的研究表明寻找一两个关键因子并不能阐明蓝藻水华的发生机理。现存的理论或假说尽管已经在蓝藻水华的防治实践中产生重要作用,但仍然未能清楚地阐释其发生的客观规律。认为蓝藻水华是在各种环境因子(外因)的耦合驱动下,水华蓝藻由于其独特的生理生态特性(内因),产生巨大的生物量而在浮游植物群落中占绝对优势,在合适的水文气象条件下集聚于水表而形成。因此水华机理的研究应同时关注水华蓝藻的生理生态学规律和蓝藻水华发生的各种环境条件。不同环境因子协同影响水华蓝藻的不同生理生态特性的表达,从而影响水华的发生过程,将可能是以后研究的重点。蓝藻水华机理的研究在微观方面正趋向于应用分子生物学手段分析蓝藻生理过程,宏观方面则将广泛应用遥感遥测技术观测全湖蓝藻的变化规律。今后加强对水华蓝藻生理生态特性的基因表达与调控和环境多因子耦合作用于蓝藻水华过程的研究将有重要意义。蓝藻水华的机理研究包括现象、过程和原因3个层次的问题,通过大量的现象和过程的研究,不断揭示其发生过程中水华蓝藻的群落演替、种群发展、细胞活性和分子机理等变化规律,才能找到其发生的真正原因,为其防治提供理论依据和更好的治理措施。在蓝藻水华防治方面,控制营养盐和生态修复可能将是今后很长时间内最根本最有效和最具操作性的方法。     

固氮蓝藻的室内培养试验

固氮蓝藻是水稻田中的有效固氮微生物,在水稻田中人工大量培养繁殖,可提高水稻田的一定肥力,解决水稻的部分氮素肥源,使水稻获得增产(黎尚豪,1959;利卓燊,1961,1962)。室內培养是大田藻种来源的第一步,也是研究蓝藻的生理学和生态学的方法之一。近廿多年来已进行了許多的試驗研究(田宮Tamiya,1957;叶清泉、黎尚豪等,1959;藤原彰夫和奥津正彥,1958—1960),对固氮蓝藻的生理特性及培养方法,已有一定的基础。我們为了簡化培养的設置及加速固氮蓝藻的生长,采用不通气的靜置培养及对培养中的几个主要环节进行了以下試驗。     

蓝藻分子遗传学十年研究进展

蓝藻遗传学研究始于60年代,其间经历了大约20年的徘徊,随着分子生物学、分子遗传学研究的进展,特别是重组DNA技术的广泛应用,为蓝藻遗传学研究提供了转机和新的洞察力,绕过应用经典遗传学技术方法所遇到的困难,另辟新径,直接分离基因,加速了研究工作的步伐。随着蓝藻本身一些重要而独特的生理特性逐渐为人们所认识,研究者日增,最近十年,蓝藻分子遗传学研究进展迅速,不仅在藻类学研究中处     

蓝藻群体颗粒驱动元素地球化学循环研究进展

在天然淡水和半咸水水体中,水华蓝藻常以群体颗粒的形态存在。在蓝藻群体颗粒中聚集着大量异养细菌,和蓝藻共同构成了具有独特生态功能的基本单元。与蓝藻单体细胞相比,蓝藻群体颗粒呈现出许多独有的特性,如内部丰富的有机质、急剧的氧化还原梯度、密切的种间互作关系等等。这些特质使得蓝藻群体颗粒在水体中成为元素地球化学循环的反应热点。同时,在蓝藻群体颗粒中也存在着远比单细胞藻类-浮游细菌之间更为密切的种间互作。本综述围绕蓝藻群体颗粒的这些特点,结合当前的研究进展,重点阐述蓝藻群体颗粒中的生物、生理、化学过程,讨论其驱动宏观生态现象的微观机制。未来蓝藻群体颗粒组学研究和多组学微生态数据库的构建或成为探索蓝藻群体颗粒中生命过程及揭示蓝藻水华暴发机制的突破口之一。     

抗生素在微藻工程中的应用研究进展

微藻具有极高的应用价值,近些年来针对于微藻的研究也越来越受到重视。抗生素的使用是微藻进行无菌化及突变体筛选等微藻研究中常用的手段之一,抗生素的作用会对微藻的生长代谢、生理活性等产生影响。现将近年来抗生素在微藻工程中的应用研究进行综述,包括抗生素在微藻无菌化培养及微藻突变株筛选中的应用及抗生素对微藻生长和生理上的影响,并对今后抗生素在微藻工程中的研究前景进行展望。     

氮胁迫下共生蓝藻的分离纯化及生理响应机制

目的：揭示氮胁迫逆境下共生蓝藻的生理响应机制。方法：采用藻细胞分离纯化技术获得了一株共生蓝藻,测定其光合色素含量并分析了氮胁迫下的生理响应机制。结果：新分离藻株的细胞形态与其他念珠藻属相似,具有典型的营养细胞和异型胞;该藻室温吸收光谱中叶绿素蓝区相对含量减少,类胡萝卜素相对含量增加;氮胁迫时,藻细胞在pH8.4和160μmol·m-2·s-1光强组合下的细胞增长率最高,同时藻细胞叶绿素a含量增加值也最高,对共生藻生理响应机制有着显著性影响（P〈0.05）。结论：该共生蓝藻为念珠藻属蓝藻,在氮胁迫下有较强的叶绿素合成能力,对碱性条件及高光强有着显著的生理响应。     

蓝藻基因工程应用研究进展

作为新的基因工程表达宿主,蓝藻以其独特的优势正逐渐引起人们的关注,自20世纪90年代以来,蓝藻已经形成了一套稳定的基因转化体系,20多年来已有30多种外源基因在蓝藻中表达成功。蓝藻表达系统将来有希望在制备重组药物、治理环境污染、农药生产等方面得到广泛应用。对蓝藻基因工程的发展及其在医药、环保、农业、生物传感器等方面的应用研究作一综述。最后分析了蓝藻基因工程发展的瓶颈表达效率低的问题,总结了研究者所作的努力：基因和剂型的选择、转录翻译元件的调控、宿主生理状态的调控等。     

话生物肥源——固氮蓝藻的识别和利用

蓝藻能光合自养,属古老的单细胞原核生物。目前已知的有二千余种,其中固氮蓝藻一百多种,常见的有念珠藻属（Ｎｏｓｔｏｃ）、单歧藻属（Ｔｏｌｙｐｏｔ－ｒｉｘ）、鱼腥藻属（Ａｎａｂａｅｎａ）等俗称“青苔”。蓝藻含有藻蓝素,故多为蓝绿色,手感微带粘滑;显微镜下见不到叶绿体和细胞核;用碘液染色,没有蓝色淀粉出现,可视为蓝藻共有的特性;是识别蓝藻并和其它藻类区别开来的方法。鉴别蓝藻有无固氮能力,可看它能否在缺氮的营养液中生长;根据这个原理,就可判断：凡能在潮湿,贫瘠缺氮的表土、岩石、墙基、屋顶、树皮、荒漠、火…     

不同无机盐对柱胞鱼腥藻同工酶的影响

盐胁迫对蓝藻的影响已有广泛的研究,人们围绕着渗透胁迫(osmoticstress),研究了高浓度盐影响蓝藻的生长、光合作用、呼吸作用、固氮作用、蛋白质和RNA的合成等〔1～4〕;但迄今为止,尚未见到有关盐胁迫下蓝藻同工酶变化情况的报道。无机盐对同工酶影响无论对于盐胁迫反应生理及机制的研究,还是对于蓝藻基因表达调控等都有重要的意义。为此,我们在研究了无机盐对蓝藻的细胞学效应、固氮酶活性的影响〔5～7〕等之后,就无机盐对蓝藻同工酶的影响进行了初步研究。1　材料与方法试验用的柱胞鱼腥藻(Anabaenacylindrica)是一种具异形胞的丝状固氮…     

Modern methods for isolation,purification, and cultivation of soil cyanobacteria

Up-to-date methods for isolation of cyanobacteria from soil samples, removal of accompanying microflora, obtaining axenic strains, and conditions and media for subsequent cultivation are reviewed. Characterization of soil as a specific habitat for cyanobacteria is provided. Comparative analysis of pH and elemental composition of the liquid phase of most soil types with the media for cultivating cyanobacteria is carried out. The functional role of the major components required for the cultivation of cyanobacteria is described. The problems associated with isolation, purification, and cultivation of soil cyanobacteria, as well as the relevant solutions, are discussed.     

Expression,purification and preliminary crystallization study of RpaC protein from <Emphasis Type="Italic">Synechocystis</Emphasis> sp. PCC6803

State transitions in cyanobacteria are physiological adaptation mechanisms that change the interaction of the phycobilisomes with the photosystem I and photosystem II core complexes. This mechanism is essential for cyanobacteria at low light intensities. Previous studies of cyanobacteria have identified a gene named rpaC, which appears to be specifically required for state transitions. The gene product of rpaC is very probably a transmembrane protein that is a structural component of the phycobilisome-photosystem II supercomplex. However, the physiological role of RpaC protein is unclear. Here we report the construction of an expression system that enables high production of fusion protein TrxHisTagSTag-RpaC, and describe suitable conditions for purification of this insoluble protein at a yield of 3 mg per 1 dm³ of bacterial culture. Cleavage with HRV 3C protease to remove the TrxHisTagSTag portion resulted in low yields of RpaC-protein (∼ 30 μg/dm³ of bacterial culture), therefore the applicability to structural studies was tested for the fusion protein only. Several preliminary conditions for crystallization of TrxHisTagSTag-RpaC were set up under which microcrystals were obtained. This set of conditions will be a good starting point for optimization in future crystallization experiments. TrxHisTagSTag-RpaC protein may prove useful in biochemical studies where the small size of RpaC protein is limiting the investigation of interactions with significantly larger parts of the photosynthetic apparatus. Furthermore, the purification procedure described here might also be applied to the production and purification of other small membrane proteins for biochemical and structural studies.     

L-谷氨酰胺生产及分离纯化研究进展

谷氨酰胺是一种条件性必需氨基酸,具有重要的生理作用,是一种极有开发前途的新药.本文对谷氨酰胺的生理作用、应用、生产及分离纯化工艺进行了综述.     

基于糖原代谢调控的蓝细菌光合细胞工厂优化研究进展

蓝细菌是重要的光合自养微生物,也是最具潜力的光合微生物底盘之一,被广泛应用于光驱固碳细胞工厂的开发.糖原是蓝细菌最重要的天然碳汇物质,糖原代谢对蓝细菌光合碳流的分配和调控具有重要意义.为了优化蓝细菌光合细胞工厂的合成效能,驱动更多的光合碳流重定向至目标代谢产物的合成,已经有多种策略和方法被成功开发用于调控蓝细菌的糖原代...     

蓝藻对UV-B增强的响应及其紫外屏蔽物质的研究

紫外线辐射对生物体危害日趋严重,逐渐引起了人们的重视.由于蓝藻在生物进化中的特殊性和在生态系统中的重要性,用于研究UV-B对生物体的影响具有诸多优势,目前国内关于UV-B对蓝藻的影响相关报道较少.本文介绍了近年来国外该领域的相关研究,主要包括UV-B对蓝藻生物量、生理效应,特别是光合作用等方面的影响,同时着重介绍了蓝藻中的紫外吸收物质的研究现状,并进一步探讨了其应用情况.     

Production of phycocyanin—a pigment with applications in biology, biotechnology, foods and medicine

C-phycocyanin (C-PC) is a blue pigment in cyanobacteria, rhodophytes and cryptophytes with fluorescent and antioxidative properties. C-PC is presently extracted from open pond cultures of the cyanobacterium Arthrospira platensis although these cultures are not very productive and open for contaminating organisms. C-PC is considered a healthy ingredient in cyanobacterial-based foods and health foods while its colouring, fluorescent or antioxidant properties are utilised only to a minor extent. However, recent research and developments in C-PC synthesis and functionality have expanded the potential applications of C-PC in biotechnology, diagnostics, foods and medicine: The productivity of C-PC has been increased in heterotrophic, high cell density cultures of the rhodophyte Galdieria sulphuraria that are grown under well-controlled and axenic conditions. C-PC purification protocols based on various chromatographic principles or novel two-phase aqueous extraction methods have expanded in numbers and improved in performance. The functionality of C-PC as a fluorescent dye has been improved by chemical stabilisation of C-PC complexes, while protein engineering has also introduced increased stability and novel biospecific binding sites into C-PC fusion proteins. Finally, our understanding of the physiological functions of C-PC in humans has been improved by a mechanistic hypothesis that links the chemical properties of the phycocyanobilin chromophores of C-PC to the natural antioxidant, bilirubin, and may explain the observed health benefits of C-PC intake. This review outlines how C-PC is produced and utilised and discusses the novel C-PC synthesis procedures and applications.     

Determination of photosystem II subunits by matrix-assisted laser desorption/ionization mass spectrometry

Photosystem II of higher plants and cyanobacteria is composed of more than 20 polypeptide subunits. The pronounced hydrophobicity of these proteins hinders their purification and subsequent analysis by mass spectrometry. This paper reports the results obtained by application of matrix-assisted laser desorption/ionization mass spectrometry directly to isolated complexes and thylakoid membranes prepared from cyanobacteria and spinach. Changes in protein contents following physiopathological stimuli are also described. Good correlations between expected and measured molecular masses allowed the identification of the main, as well as most of the minor, low molecular weight components of photosystem II. These results open up new perspectives for clarifying the functional role of the various polypeptide components of photosystems and other supramolecular integral membrane complexes.     

Ferrates for water remediation

The availability of safe drinking-water at the global level is one of the biggest challenges of our century. At present, toxins and pathogens in fresh waters are responsible for more than two million deaths per year. This scenario allows understanding how the development of effective and sustainable technologies for water treatment is of pivotal importance for future generations. A number of different agents and methods are used for water purification and environmental remediation, however they all show main drawbacks, revealing the need for a major technological advancement. Iron-based materials are earning a particular interest due to the effectiveness in water purification, the environmental friendly and earth-abundant nature. Moreover, some iron-containing materials are magnetic, allowing for an easy removal of the materials after water sanitizations. In the present review, the state of the art of iron based nanomaterials for water remediation is presented, with a special attention on ferrates, their synthesis, stability, mechanism of action and analytical determination. More in details, the review focuses on the following environmental applications of iron based nanomaterials: wastewater disinfection, organic matter removal, treatment of pharmaceuticals, inactivation of bacteria and viruses, removal of heavy metals and arsenic, degradation of fluoro-compounds and inactivation of cyanobacteria.     

Cyanobacteria in Antarctica: ecology, physiology and cold adaptation.

Cyanobacterial species composition of fresh water and terrestrial ecosystems and chemical environment of water in Schirmacher Oasis in Continental Antarctica was investigated. Over 35 species of cyanobacteria were recorded. Diazotrophic species both heterocystous and unicellular contributed more than half to the count except in lake ecosystem. The species composition varied among the fresh water as well as terrestrial ecosystems. The physico-chemical analyses of water revealed its poor nurient content which might have supported the growth of diazotrophic cyanobacteria in an Antarctic environment. Among the cyanobacteria Oscillatoria, Phormidium and Nostoc commune were the dominant flora in most of the habitats. The physiological characteristics of isolated cyanobacteria strains indicated that N2-fixation, nitrate uptake, nitrate-reduction, ammonium-uptake, GS-transferase activity and photosynthesis was unaffected at low temperature (5 degrees C) which indicated low temperature adaptation for Antarctic cyanobacteria. This phenomenon was not evident in different strains of tropical origin. The temperature optima for N2-fixation for the different Antarctic cyanobacterial strains was in the range of 15-25 degrees C, nearly 10 degrees C lower than their respective reference strains of tropical origin. Similar results were obtained for cyanobacteria-moss association. The low endergonic activation energy exhibited by the above metabolic activities supported the view that cyanobacteria were adapted to Antarctic ecosystem.